This paper considers the way in which the risks of accidents are asses
sed by organizations concerned with the four main modes of transport:
road, rail, civil aviation, and water transport. Risk assessment has t
wo main components: risk estimation, which is the process of estimatin
g what the risks are from an activity, and risk evaluation, which is t
he process of deciding or recommending what should be done about them.
The paper discusses the methods and intellectual frameworks used for
risk estimation and risk evaluation in each mode of transport. Conclus
ions are offered at the end, based on cross-modal comparisons.